Apparatus for ascertaining the transverse dimensions of rod-shaped articles

ABSTRACT

The invention relates to an apparatus which embodies an optical measuring assembly serving to ascertain the transverse dimensions (such as diameters) of at least substantially cylindrical rod-shaped articles, preferably cigarettes or other rod-shaped articles of the tobacco processing industry, and includes a radiation source employing at least one first preferably circular array of light emitting diodes or the like, an evaluating unit employing at least one preferably circular array of signal generating charge coupled devices or the like, and a control unit which regulates the operation of batches of neighboring diodes and receives preferably short-lasting signals from the charge coupled devices located in the shadow produced by the article which is coaxial with and is spacedly surrounded by the two arrays. The article can be stationary or it can move (such as axially) relative to the coaxial arrays.

CROSS-REFERENCE TO RELATED CASES

[0001] This application claims the priority of the commonly owned Germanpatent application Serial No. 103 23 152.8 filed May 22, 2003. Thedisclosure of this German patent application, as well as that of eachU.S. and/or foreign patent and/or patent application identified in thespecification of the present application, is incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] The invention relates to improvements in apparatus for measuringthe transverse dimensions (such as the diameters) of one or morerod-like objects, especially rod-shaped products or articles of thetobacco processing industry, which employ at least one opticalarrangement or assembly including an irradiating unit which illuminatesthe product or products and an evaluating unit. The latter can beconstructed and assembled to effect a preferably short-lastingascertainment of the extent to which the rod-shaped product(s)intercepts or intercept the radiation issuing from the irradiating unitand to initiate or to effect the generation of signals denoting thetransverse dimension(s) of the product(s). The product or products canbe positioned in or can move across the path of radiation which issuesfrom the irradiating unit and is directed toward the evaluating unit.

[0003] As utilized herein, the term “rod-shaped products of the tobaccoprocessing industry” is intended to denote plain and filter cigarettes,cigars and cigarillos, filter rods for tobacco smoke and otherrod-shaped commodities which constitute or form part of smokers'products. Such rod-shaped products can be monitored in order toascertain their diameters (actually their transverse or cross-sectionaldimensions because the cross-sectional outline of a cigarette or thelike often should but often does not constitute a perfect circle)irrespective of the then stage of treatment of the products. Forexample, the monitoring can take place prior or subsequent to or duringthe assembly of plain cigarettes, filter rod sections and portions ofso-called tipping paper into filter cigarettes of unit length ormultiple unit length. Furthermore, the apparatus of the presentinvention can be set up to monitor the cross-sectional dimensions of oneor more endless rod-shaped articles (such as continuous cigarette rodsor filter rods) which is or are caused to move lengthwise (axially)and/or which rotates or rotate about its or their longitudinal axis oraxes, as well as to monitor the cross-sectional dimensions (hereinafterfrequently referred to as diameters) of endless articles subsequent totheir subdivision into one or more files of rod-shaped articles of unitlength or multiple unit length in one or more severing devices, e.g., ofthe type known as cutoffs.

[0004] The ascertainment or determination of the cross-sectionaldimensions of rod-shaped smokers' products, and the elimination ofcauses of departure of such dimensions from predetermined (optimum)dimensions are particularly important when the products are cigarettesand/or filters for cigarettes. Such determination normally involvesmeasurements which are carried out while the products are being movedlengthwise (axially), either continuously or in a stepwise fashion. Themeasurement of cross-sectional dimensions of rod-shaped smokers'products of the just outlined character can present numerous problemsfor any one of a variety of reasons, such as the speed of a modernmachine which is designed to turn out products at a rate unheard of andunimaginable only a few decades ago. Furthermore, the extent to whichthe actual transverse dimensions of a plain or filter cigarette (or acomponent or portion thereof) can depart from the prescribed (optimum)dimensions is within a minute fraction of a millimeter, and the problemsare or can be even greater if the cross-sectional outline of theproducts (such as oval cigarettes) should depart (often considerably)from a prescribed (such as circular) outline.

[0005] European patent application Serial No. 0 909 537 A1 (filed Sep.17, 1999 by Mauricio Cotti et al. for “A UNIT FOR CHECKING THETRANSVERSE DIMENSIONS OF ROD-SHAPED PRODUCTS”) discloses a measuringapparatus wherein an irradiating unit is designed to generate a widebunched beam of parallel electromagnetic rays which impinge upon amirror to be deflected at an angle of 90° and to be thus reflected uponan evaluating unit. The rod-shaped article to be monitored extends inparallelism with the mirror and at right angles to the beam in suchposition that a first portion of the beam is propagated from the sourcedirectly to the article, and that a second portion of the beam reachesthe article upon deflection by the mirror. In other words, the radiationwhich reaches the evaluating unit of the apparatus disclosed by Cotti etal. includes two neighboring sections which are arranged to representthe diameters of a cross-sectional area of the article and are normal toeach other. This apparatus exhibits the advantage that it can monitorthe diameters of rod-shaped articles which need not turn about theirlongitudinal axes or which is should not turn about such axes; thisrenders the apparatus of Cotti et al. suitable for the ascertainment ofdiameters of endless rod-shaped commodities. However, the apparatus ofCotti et al. exhibits the serious drawback that it can ascertain onlytwo diameters of those cross-sectional areas which are to be monitored;such mode of ascertaining the departures of actual configurations ofrod-shaped articles from the desired or prescribed configurations cannotensure the detection of all defects of rod-shaped articles to satisfythe requirements of smokers and/or of the makers of rod-shaped smokers'products.

[0006] Commonly owned German patent application Serial No. DE 195 23 273A1 of Siegfried Hapke et al. for “METHOD OF AND APPARATUS FORASCERTAINING THE DIAMETER OF A ROD-SHAPED ARTICLE OF THE TOBACCOPROCESSING INDUSTRY” (published Jan. 9, 1997) discloses a method and anapparatus which are particularly suitable for ascertainment of thediameters of cigarettes that are monitored while moving lengthwise andwhile rotating about their longitudinal axes during transport through astationary measuring apparatus. The cigarette which turns about its axisduring lengthwise movement through the measuring apparatus is exposed toradiation, and the apparatus monitors the size of at least one shadowwhich develops as a result of interception of some radiation. Theapparatus generates electric signals which are proportional to thesize(s) of the shadow(s). Several of the thus obtained signals areprocessed into a signal which denotes the diameter of the monitoredrod-shaped article.

[0007] An advantage of the just described method and apparatus is thatthey render it possible to ascertain the diameters of cigarettes oranalogous rod-shaped smokers' products with a high degree of accuracy.On the other hand, such method and apparatus cannot be resorted to inconnection with the ascertainment of diameters of continuous rod-shapedproducts which turn about their longitudinal axes.

[0008] Commonly owned U.S. patent application Ser. No. ______ (filed______ 2004 by Siegfried Hapke et al. for “METHOD OF AND APPARATUS FORASCERTAINING THE TRANSVERSE DIMENSIONS OF ROD-SHAPED ARTICLES”)discloses a method of and an apparatus for ascertaining the transversedimensions, such as diameters, of one or more rod-shaped articles, forexample, continuous or finite-length cigarette rods and/or otherrod-shaped smokers' products. When the method and the apparatus areutilized to ascertain the transverse dimensions of a single rod-shapedarticle, such as a continuous cigarette rod which is stationary, whichturns about its longitudinal axis and/or which is moved lengthwise, theapparatus can employ at least one radiation source which emits a beam ofradiation against the stationary or moving article whereby the articleintercepts a first portion of the beam and permits the remaining portionto impinge upon a device which evaluates the non-intercepted portion ofthe beam and generates signals denoting the diameter of the article. Theapparatus also employs an arrangement, such as a motor and abelt-and-pulley device, for selectively altering the orientation of thebeam relative to the article; this enables the evaluating device tofurnish signals which can be processed to indicate whether or not thearticle is round or out of round.

OBJECTS OF THE INVENTION

[0009] An object of the present invention is to provide a novel andimproved method of ascertaining the transverse dimensions of rod-shapedcommodities, such as discrete cigarettes, continuous cigarette rods,discrete filters for tobacco smoke, continuous filter rods and the like,which need not rotate about their longitudinal axes in the course of thetesting operation.

[0010] Another object of the invention is to provide a method ofaccurately ascertaining the transverse dimensions of continuousrod-shaped smokers' products or the like.

[0011] A further object of the instant invention is to provide a methodwhich can ascertain the diameters of rod-shaped smokers' products with adegree of accuracy much higher than that achievable by resorting toheretofore known undertakings.

[0012] An additional object of this invention is to provide a novel andimproved apparatus which can be utilized for the practice of the aboveoutlined method.

[0013] Still another object of the invention is to provide an apparatuswhich can be embodied in or utilized in conjunction with presently known(including the latest versions of) machines for the making of cigarettesand other rod-shaped products of the tobacco processing industry.

[0014] A further object of this invention is to provide a novel andimproved optical signal generating and signal processing assembly foruse in the above outlined apparatus.

[0015] An additional object of the invention is to reduce the number ofrejects which are turned out by machines for the making and processingof rod-shaped smokers' products or the like.

SUMMARY OF THE INVENTION

[0016] The invention resides in the provision of an apparatus forascertaining transverse dimensions (such as diameters) of at least oneat least substantially rod-shaped article. The apparatus includes animproved optical measuring assembly which comprises a radiation sourcewhich is arranged to direct radiation against the article so that thearticle intercepts at least a portion of radiation, namely a portionwhich is indicative of its transverse dimension. The radiation sourcecomprises at least one first array of radiation emitting first elements(such as light emitting diodes), and the measuring assembly furthercomprises an evaluating unit including at least one second array ofradiation-sensitive second elements which are located at leastsubstantially opposite the radiation emitting first elements and in thepath of propagation of radiation from the source toward the article togenerate signals which denote the amount of radiation being interceptedby the article. The radiation-sensitive second elements can includecharge coupled devices. The article in the aforementioned path canconstitute at least a portion of or an entire rod-shaped smokers'product.

[0017] The evaluating unit is preferably arranged to effect ashort-lasting determination of the transverse dimension of the at leastone rod-shaped article in the aforementioned path; such article can bestationary or the apparatus can further comprise means for moving the atleast one article across the path.

[0018] At least one of the first and second arrays can at leastpartially surround the article in the aforementioned path; to this end,at least one of the arrays can be imparted an arcuate shape and such atleast one array can constitute a portion of or a complete circle withthe article in the aforementioned path located at or at least close tothe center of such arcuate or circular array.

[0019] The effective width of each radiation emitting (first) elementcan exceed the effective width of each is radiation-sensitive secondelement.

[0020] The optical measuring assembly of the improved apparatuspreferably further comprises control means which is operativelyconnected with the radiation source and with the evaluating unit and isarranged to actuate selected groups or sections of first elements, toreceive signals from the second elements, and to ascertain thetransverse dimension of the article in the aforementioned path on thebasis of such signals. If the apparatus is arranged to ascertain thediameters of at least substantially rod-shaped articles normally havingpredetermined (standard) diameters, the control means is preferablyarranged to actuate selected groups of first elements, namely groupseach of which has a length at least approximating one of thepredetermined diameters, and such control means is preferably furtherarranged to ascertain the diameter of the article in the aforementionedpath on the basis of (a) the predetermined diameters and (b) on thebasis of signals from those second elements which are screened from thegroups of neighboring first elements by the article in the path.

[0021] The control means can be arranged to ascertain the diameter ofthe article in the aforementioned path exclusively on the basis ofsignals which are transmitted by those second elements which are fullyscreened from the groups of neighboring first elements.

[0022] The first array (of radiation emitting first elements) is or canbe elongated (e.g., circumferentially around the article in theaforementioned path) and the selected groups of first elements arepreferably adjacent each other. The control means of such opticalmeasuring assembly can be arranged to actuate successive groups of firstelements (namely successive groups which form a row extending lengthwiseof the first array) so that the radiation issuing from successive groupsof first elements impinges at different angles upon the article which islocated in the aforementioned path. If the first array at leastpartially surrounds the article in the aforementioned path, successivegroups of first elements can cause the second elements to generatesignals which are suitable to be processed by the control unit toascertain the curvature of that portion of the circumference of thearticle in its path which is being exposed to radiation by thesuccessive groups of first elements. The control means can be arrangedto process the signals from the second elements into information whichdenotes an average transverse dimension of that part of the articlewhich is located in the aforementioned path.

[0023] If the improved apparatus is to simultaneously ascertaintransverse dimensions of a plurality of (such as two) at leastsubstantially rod-shaped articles, it comprises a discrete opticalmeasuring assembly for each of such plurality of articles. The radiationsources and the evaluating units of such discrete assemblies are or canbe closely (such as immediately) adjacent each other.

[0024] The improved apparatus can further comprise means (such as atleast one diaphragm) for optically separating the first and secondarrays from each other. If at least one of the arrays forms an at leastsubstantially complete circle, the optical separating means can comprisea diaphragm which is provided with an opening for the article located inthe aforementioned path.

[0025] The radiation which issues from the radiation source of theimproved optical measuring assembly can be at least substantially normalto the longitudinal extension of the article in its path.

[0026] The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved apparatus itself, however, both as to its construction and themodes of assembling, installing and operating the same, together withnumerous additional important, desirable and advantageous features andattributes thereof, will be best understood upon perusal of thefollowing detailed description of certain presently preferred specificembodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

[0027]FIG. 1 is a somewhat schematic perspective view of a cigarettemaking machine employing a diameter ascertaining apparatus whichembodies one presently preferred form of the invention;

[0028]FIG. 2a is a diagrammatic view of an optical system which can beutilized in an apparatus that is embodied in or cooperates with thecigarette making machine of FIG. 1 or an analogous machine for themaking of rod-shaped products;

[0029]FIG. 2b is a coordinate system wherein the curves denote theprogress or arrangement of signals being generated by the optical systemof FIG. 2a; and

[0030]FIG. 3 is a schematic side elevational view of is the opticalsystem which is shown in FIG. 2a.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0031]FIG. 1 illustrates certain relevant details of a cigarette rodmaking machine which is known as PROTOS and is distributed by theassignee of the present application. This machine comprises a gate 1which is arranged to supply batches of shredded and/or otherwisecomminuted tobacco leaves into a preliminary distributor 2. A tobaccowithdrawing drum 3 serves to draw tobacco particles from the distributor2 into a magazine 4 in such a way that the supply of tobacco in thelatter is maintained at an at least substantially constant level. Apreferably automatically controlled elevator conveyor 5 of known design(see, for example, commonly owned U.S. Pat. No. 5,072,742 granted Dec.17, 1991 to Heitmann for “METHOD OF AND APPARATUS FOR MAKING A FILLER OFSMOKABLE MATERIAL”) is provided to draw batches of tobacco particlesfrom the magazine 4 and to deliver successive batches into a gatheringduct 6 which is installed in the machine frame at a level above a rotarycarded drum 7 cooperating with a rapidly rotating so-called pickerroller 8 to propel an at least substantially uniform stream of tobaccoparticles onto the upper reach of a continuously driven constant-speedendless belt conveyor 9.

[0032] The conveyor 9 gathers and advances lengthwise a continuousstream of tobacco particles, and the leader of such stream is propelledagainst a pneumatic sifter 11 which includes nozzles and/or analogousair discharging and directing devices forming an upright air curtainwhich is traversed by larger (heavier) tobacco particles but interceptsthe lighter particles of the stream being supplied by the belt conveyor9. The intercepted lighter tobacco particles descend onto the carding ofa rotary drum 12 cooperating with a wall 13 to form therewith a funnel14. The heavier (more satisfactory) tobacco particles which havetraversed the air curtain formed by the sifter 11 are propelled by thecarding of the drum 12 to enter a channel 16 and to impinge upon and beentrained by the lower reach of a foraminous band conveyor 17. Thelatter cooperates with a suction chamber 18 to attract and advancesuccessive increments of a shower of satisfactory tobacco particlestoward a stream trimming or equalizing device 19.

[0033] The equalizing device 19 removes the surplus of tobacco from thestream at the underside of the lower reach of the band conveyor 17 whichconveys the thus trimmed stream onto the upper side of a continuouslyadvancing strip or web 21 of cigarette paper or other suitable wrappingmaterial. This web is drawn off a bobbin 22 and moves in the samedirection as the lower reach of the band conveyor 17 to advance theequalized tobacco stream into a wrapping mechanism 26 employing a drivenendless belt or band 24 known as garniture. Prior to entering thewrapping mechanism 26 including the garniture 24, successive incrementsof the cigarette paper web 21 advance through a printer 23 whichprovides successive spaced-apart portions of the web with suitableprinted matter (e.g., the trademark(s) of the manufacturer of plain orfilter cigarettes).

[0034] The garniture 24 drapes the running web 21 of cigarette paperaround the trimmed or equalized tobacco stream (called filler) in such away that one longitudinal marginal portion of the web extendssubstantially tangentially of and away from the cylindrical envelopesurrounding the confined tobacco stream. The wrapping mechanism 26further comprises a so-called paster (not shown) which coats one side ofthe aforementioned one marginal portion of the web 21 with a suitableadhesive, and such marginal portion is thereupon folded over theadjacent portion of the thus finished tubular envelope for the confinedequalized tobacco stream or filler of the resulting cigarette rod 28. Aplate-like drying device (e.g., a so-called tandem sealer) 27 isprovided to promote the setting of adhesive and to thus prevent theenvelope from bursting open at the adhesive-coated seam during furtherprocessing of the continuous cigarette rod 28.

[0035] The rod 28 is caused to advance through a measuring andregulating apparatus 29 on its way to a severing apparatus 31 (known ascutoff) which repeatedly cuts across the advancing rod to convert thelatter into a series of succesive plain cigarettes 32 of double unitlength. Such plain cigarettes advance into the range of controlledorbiting arms 33 of a transfer unit 34 which delivers the cigarettes 32onto a drum-shaped receiving conveyor 36 of a filter cigarette makingmachine 37. The latter comprises a severing device including a drum 38and a circular knife (not shown) which cooperates with the drum 38 tohalve each cigarette 32 into a pair of plain cigarettes of unit length.The filter cigarette making machine 37 can be of the type disclosed incommonly owned U.S. Pat. No. 5,135,008 granted Aug. 4, 1992 toOesterling et al. for “METHOD OF AND APPARATUS FOR MAKING FILTERCIGARETTES”.

[0036]FIG. 1 further shows two endless belt conveyors 39, 41 which serveto convey surplus tobacco (removed by the trimming device 19) back intothe range of the elevator conveyor 5 which supplies such material intothe gathering duct 6. More specifically, the conveyor 41 deliverssurplus tobacco into a receptacle 42 which is adjacent the path ofmovement of spaced-apart paddles at the outer side of the endlessflexible element of the elevator conveyor 5.

[0037] The aforementioned apparatus 29 of the continuous cigarette rodmaking machine of FIG. 1 comprises an optical measuring assembly 50 therelevant constituents of which are schematically depicted in FIGS. 2aand 3. Such constituents include a ring-shaped array 51 of closelyadjacent discrete light-emitting diodes (LED) 51 a. For example, thearray 51 can comprise 4096 closely adjacent (neighboring) diodes 51 orequivalent radiation emitting elements. As can be readily seen in FIG.2a, the diodes 51 a are directly adjacent each other and are or can beidentical with one another. This Figure further shows that the diodes 51a have identical widths, as seen in the circumferential direction (i.e.,longitudinally) of the array 51.

[0038] The array 51 is coaxial with and is spaced apart from (see FIG.3) a second annular array 52 consisting of charge coupled sensor devices(CCD), e.g., an array of 4096 CCD pixels. FIG. 3 shows that the twocircular arrays of diodes 51 a and pixels are spaced apart from eachother as seen in the direction of the common axis of these arrays. Itwill be appreciated that the CCD pixels of the array 52 can be replacedwith other optical sensor elements without departing from the spirit ofthe present invention. Each pixel of the second array 52 can be orientedand positioned in the same way as the diodes 51 a of the array 51.

[0039] In order to ensure the making of highly accurate measurements, itis desirable to assemble the second array 52 of a large number ofradiation-sensitive pixels (or equivalents thereof) so that each suchpixel has a small (minimal) effective width as seen in thecircumferential direction of such array. On the other hand, if desiredor necessary, the array 51 can be assembled of a relatively small numberof diodes 51 a or equivalents thereof (i.e., fewer than 4096). Theillustrated arrays 51 and 52 are stationary and each thereof forms acomplete circle.

[0040] As can be seen in FIG. 3, a circular washer-like diaphragm 53 isinterposed between and is or can be coaxial with the arrays 51 and 52.The diaphragm 53 constitutes a means for optically separating the pixelsof the array 52 from the neighboring (nearest) diodes 51 a of the array51. This is necessary because (and as shown in FIG. 2a) light beamsissuing from the diodes 51 a should not impinge upon the immediatelyadjacent CCD elements but rather upon the diametrically oppositeelements of the array 52. For example, the light beams issuing from thediodes 51 a at the twelve o'clock position of the array 51 shown in FIG.2a should impinge upon the pixels at the six o'clock position of thearray 52.

[0041] The cigarette rod 28 is caused to move lengthwise through thecoaxial arrays 51, 52 and the central opening of the diaphragm 53 whichlatter is coaxial with the two arrays. In te illustrated embodiment ofthe improved assembly 50, the cigarette rod 28 is coaxial with the parts51 to 53, i.e., it advances at right angles to the planes of the twoarrays and the diaphragm with the result that the beams 56 of radiationissuing from the activated light emitting diodes 51 a of the array 51impinge upon the oppositely located CCD elements of the array 52 at anangle which, in actual practice, is normally a little smaller than aright angle. In other words, the beams 56 impinge upon the cigarette rod28 at an angle which is at least close to and can be a little less than90°.

[0042]FIG. 3 further shows that the optical measuring assembly 50 alsocomprises a control unit or evaluating unit 54 which actuates and thusactivates selected diodes 51 a of the array 51 and which is alsoconnected to and receives and evaluates signals from the CCD elements ofthe array 52. The diodes 51 a of the array 51 are controlled andactuated in such a way that several neighboring coherent activateddiodes 51 a form a segment or group 51 b (see FIG. 2a) which serves togenerate what can be called a running or travelling light advancinglengthwise of (i.e., along) the ring-shaped array 51, namely around thecigarette rod 28. This activated segment or group 51 b of running lightcan be caused to advance at any one of a plurality of different speedsbecause its speed is not dependent upon the speed or speeds of anymechanical components. Thus, the diameter of the rod 28 can be measuredin one of several directions without resorting to mobile parts.

[0043] As a rule, or at least in many instances, the width d_(L) of anactivated group or segment 51 b of several diodes 51 a should match orat least approximate the is desired (predetermined) diameter of thecigarette rod 28. The latter generates a core or shadow 61 byinterrupting certain beams of radiation, and such shadow is formed onthat part (d_(S)) of the array 52 which is disposed diametricallyopposite the group or segment 51 b and is detected by the correspondingCCD elements of the second array 52. The core shadow 61 is flanked bywhat can be termed half shadows or partial shadows 62 which, in turn,are inwardly adjacent regions 63 of dispersed light impinging upon theannular CCD array 52. The distribution of brightness of light impingingupon the CCD elements of the array 52 (as seen in the circumferentialdirection of the relevant section of the CCD array 52) is shownschematically in the coordinate system of FIG. 2b wherein the intensityis measured along the ordinate and the location (circumferentially ofthe array 52) is measured along the abscissa.

[0044] In the embodiment which is illustrated in the drawing, the widthd_(s) of the core shadow 61 (by taking into consideration the widthd_(L) of the group or segment 51 b and the actual diameter D_(ist) ofthe cigarette rod 28) is calculated as follows:

d=d _(L)+2×(D _(ist) −d _(L))=2D _(ist) −d _(L).

[0045] This equation can be resorted to in order to ascertain themeasured (actual) diameter D_(ist) in accordance with the equation:

D _(ist)=(d _(s) −D _(L))/2.

[0046] If it is desired to perform a single measurement (in order toascertain the actual diameter of the advancing cigarette rod 28), it isimportant to ensure that the cigarette rod is maintained exactly at orat least very close to the central portion of the space which issurrounded by the coaxial arrays 51 and 52, i.e., that the longitudinalaxis of the cigarette rod coincides with the common axis of the twoarrays. If such guidance of the cigarette rod 51 is not possible, it isdesirable or necessary to carry out several measurements in differentangular positions of the radiation beams 56. At the very least, oneshould carry out two measurements in positions in which the beams 56 aredisposed at an angle of 1800 relative to each other. Depending upon thenumber of measurements in which the beams 56 are in different angularpositions relative to the cigarette rod 28 and which develop as arunning or travelling light due to the orbiting activated group orsegment 51 b, the evaluating unit 54 calculates or ascertains acorresponding number of diameter values. In the next step of the methodwhich is being practiced by resorting to the novel assembly 50, suchdiameter values are averaged in the control unit 54 which is thus is ina position to furnish information pertaining to an averaged diameter ofthe cigarette rod 28. The averaging unit (not shown) of the control unit54 can be of any known design.

[0047] The control unit 54 can be arranged to evaluate several signalsfrom the annular CCD array 52 in such a way that the thus processedsignals denote the extent to which the actual cross-sectional outlinedeparts from a desired outline (e.g., that the processed signals denotethe exent to which the cross-sectional outline of the cigarette rod 28is out of round).

[0048] Still further, the novel optical measuring assembly 50 can alsoserve to monitor the transverse dimensions of one of several discreterods containing tobacco, other smokable material and/or filter materialfor tobacco smoke. If the machine of FIG. 1 is replaced with a machinewhich is set up to simultaneously turn out two cigarette rods, theapparatus comprises two optical measuring assemblies 50, one for eachcigarette rod. Such plural assemblies are preferably installed close toor in immediate proximity of each other. Machines which cansimultaneously turn out a plurality of cigarette rods are disclosed, forexample, in commonly owned U.S. Pat. No. 4,893,640 (granted Jan. 16,1990 to Heitmann et al. for “MULTIPLE-ROD CIGARETTE MAKING MACHINE”) andin commonly owned U.S. Pat. No. 4,924,885 (granted May 15, 1990 toHeitmann et al. for “METHOD OF AND APPARATUS FOR BUILDING, GUIDING ANDTRIMMING STREAMS OF FIBROUS MATERIAL”).

[0049] U.S. Pat. No. 4,412,505 (granted Nov. 1, 1983 to Häusler et al.for “APPARATUS FOR APPLYING ATOMIZED LIQUID TO A RUNNING LAYER OFFILAMENTARY MATERIAL OR THE LIKE”) discloses a machine which can turnout a continuous rod wherein a rod-like filler of filter material fortobacco smoke is surrounded by a tubular wrapper of paper or the like.Such machine can also embody an apparatus which serves to ascertain andto initiate (when necessary) changes of transverse dimensions of thefilter rod.

[0050] An important advantage of the improved apparatus and its opticalmeasuring assembly 50 is that, due to the utilization of a plurality ofserially arranged discrete light emitting elements 51 a and a pluralityof serially arranged sensor elements which constitute the array 52, thediameter (transverse dimension) of the at least one rod-shaped article28 can be ascertained with a surprisingly high degree of accuracy, evenif the article portion in the path of rays 56 issuing from the activatedlight emitting elements 51 a is out of round. Thus, the improvedapparatus can be utilized with advantage to ascertain the transversedimensions of those rod-shaped articles which are produced or processedin an apparatus wherein a turning about their longitudinal axes is notrequired or desired, as well as of those articles which constitutefinished or partly finished endless products. In other words, an articlewhich is being tested can be monitored to ascertain its transversedimension(s) while it is at a standstill. However, it is equallypossible to utilize the improved apparatus for the measurement oftransverse dimensions of rod-shaped articles while such articles are inmotion, e.g. (and as shown in FIGS. 1, 2 a and 3), while the articlesadvance lengthwise under the action of the driven garniture 24. This isof particular advantage if the determination of the diameter of acontinuous article should take place during a stage of the process ofmaking discrete rod-shaped articles which precedes the step or steps ofsubdividing the continuous article into sections or portions of unitlength or multiple unit length. The measurement to ascertain thetransverse dimensions of an originally endless article can take placewhile the article moves continuously or stepwise, and the same holdstrue if the measurement involves a monitoring of transverse dimensionsof discrete articles which have already undergone at least onesubdividing treatment or prior to the is last subdividing step. Forexample, the improved apparatus can be utilized to ascertain thediameters of plain cigarettes 32 of double unit length in a cigarettemaking machine of the type shown in FIG. 1, or to ascertain thediameters of plain cigarettes of unit length in a machine of the typedisclosed in the aforementioned commonly owned US patent No. 5,135,008to Oesterling et al.

[0051] In a modification of the apparatus which is shown in FIGS. 2a and3, the array 51 and/or the array 52 can be arranged to surround only aportion of that part of an article which is being monitored to ascertainits transverse dimensions. Such array or arrays can have an arcuateshape and the article or the article portion to be measured can belocated at or close to the center of the partial or complete circle ofelements 51 a and/or the CCD elements of the second array 52. Thearticle is spaced apart from such elements, the same as in the apparatus29 including the assembly 50 shown in FIGS. 1, 2a and 3. The arrays 51and 52 which are shown in FIGS. 2a and 3 (i.e., the arrays which arecomplete circles) constitute a presently preferred embodiment of theinvention. An advantage of such embodiment is that the distances betweenthe elements 51 a of the array 51, as well as the distances between thesensors of the array 52, are uniform which contributes to simplicity ofthe improved apparatus and to simplicity of evaluation of signals whichare being transmitted to the control unit 54.

[0052] An advantage of an optical assembly wherein the number ofradiation-sensitive elements in the array 52 is relatively high and thewidths (and hence the pitch) of such elements are or is relatively smallis that this even further ensures the making of highly accuratemeasurements of transverse dimensions of rod-shaped articles. It hasbeen ascertained that the accuracy of measurements is enhanced if theeffective widths of the elements 51 a exceed the widths of the sensorelements forming part of the array 52.

[0053] An important advantage of the feature that the control unit 54 isarranged to activate sections or segments or groups 51 b of coherent(neighboring) radiation emitting elements 51 a, and that the controlunit 54 receives signals from those sensor elements of the array 52which are located in the shadow (at 61) of the article 28 (and generatessignals denoting the diameters of articles 28 in the path of the rays 56issuing from the group of coherent elements 51 a) is that sucharrangement also contributes to greater accuracy and simplicity of themeasurements. Such accuracy is further is enhanced if the length of thesegment 51 b (as measured in the circumferential direction of the array51) at least approximates the desired diameter D_(ist) of the rod-shapedarticle 28 which is located in the path of rays 56 issuing from thegroup or section 51 b of activated radiation emitting elements. Thisensures that the control unit 54 can ascertain the transverse dimensions(such as diameters D_(ist)) of the articles 28 being tested on the basisof signals from those elements of the array 52 which are disposed in theshadow of the article 28 25 as well as on the basis of (i.e., by fullconsideration of) the desired or prescribed diameters of the rod-shapedarticles.

[0054] The accuracy of determination of actual transverse dimensionsD_(ist) of tested articles 28 can be further enhanced if the controlunit 54 of the optical measuring assembly 50 receives signals only fromthose sensor elements of the array 52 which are disposed in the fullshadow or core shadow 61 being generated by the tested article.Moreover, this contributes to simplicity of the improved opticalmeasuring assembly 50 because the geometrical evaluation of the fullshadow or core shadow can be performed in a rather simple manner.

[0055] The aforementioned feature that the control unit 54 is arrangedto activate a group 51 b of coherent (neighboring) light emittingelements 51 a brings about the additional advantage that the radiationissuing from such group of elements 51 a can be caused to advancecircumferentially of the article 28 which is being tested or monitored(i.e., that the control unit 54 can cause the groups or segments 51 a togenerate running radiation which travels circumferentially of the array51) ; this is of particular advantage when the array 51 is stationary.This is the normal way of building up and operating the opticalmeasuring assembly 50. A change in the angular position of the rays 56issuing from the group or segment 51 b of activated light-emittingelements 51 a relative to the article 28 being tested can be effected orrealized in that the control unit 54 activates, for short intervals oftime, successive groups 51 b of coherent elements 51 a, e.g., bydeactivating at least one element 51 a at one side of an activated group51 b and simultaneously activating at least one previously idle element51 a at the other side of such group. This results in the generation ofa running arrangement of rays 56 which change their positions relativeto the article 28 whose longitudinal axis then preferably coincides withthe common axis of the arrays 51 and 52. Such mode of operating theoptical measuring assembly 50 is of particular advantage if the assemblyis to ascertain the extent to which the cross-sectional outline of thetested article 28 departs from a desired (such as circular) outline.

[0056] The just described optical measuring assembly 50 renders itpossible to carry out a practically infinite number of measurements inany desired cross-sectional plane of the rod-shaped article 28. This, inturn, enables the improved assembly to accurately ascertain thecross-sectional outline of the tested article and hence also the extentto which such outline departs from a desired or optimal (such ascircular) outline. Still further, such assembly can be resorted to forthe determination of maximal and minimal transverse dimensions of thetested articles which, in turn, renders it possible to determine theextent to which the cross-sectional outline departs from a range ofacceptable outlines. In addition, the just discussed assembly renders itpossible to test oval cigarettes and oval filter mouthpieces, e.g., inorder to ascertain whether or not such rod-shaped articles arecompatible (i.e., whether or not they can be assembled into acceptableoval filter cigarettes).

[0057] Alternatively, or in addition to the aforedescribed constructionand mode of operation, the improved optical measuring assembly canemploy an arrangement which averages the ascertained transversedimensions to thus furnish an averaged transverse dimension which is orwhich can be indicative of the mean diameter of a substantially roundrod-shaped article, namely of the average of those diameters which areascertained in different angular positions of the rays 56 relative tothe common axis of the arrays 51, 52 and the article which is located inthe path of such rays. The accuracy of a determination of such mean oraverage diameter of a substantially round rod-shaped article can beincreased practically at will, i.e., by the simple expedient ofincreasing the number of individual measurements in different angularpositions of the rays 56.

[0058] If the improved optical assembly is to simultaneously ascertainthe transverse dimensions of plural (e.g., two) rod-shaped articles,such articles are preferably located in close or immediate proximity toeach other. The improved assembly then comprises one pair of arrays 51,52 and one control unit 54 for each of the articles. As alreadymentioned hereinbefore, such composite optical assemblies can beutilized in or with machines of the type disclosed in the commonly ownedU.S. Pat. Nos. 4,893,640 and 4,924,885 to Heitmann et al.

[0059] The purpose of the diaphragm 53 is to further enhance thereliability of the results which are furnished by the control unit 54 inthat it reduces the ability of stray light or dispersed light (63) toadversely influence the elements of the array 52 by radiation issuingfrom the neighboring elements 51 a of the array 51. As can be seen inFIG. 3, the diaphragm 53 is placed between and optically separates thearrays 51 and 52 from each other. The central opening of the diaphragm53 is large enough to ensure unimpeded insertion and (if contemplated)axial advancement of a rod-shaped article 28 therethrough.

[0060] The rays 56 are preferably oriented in such a way that they areat least substantially normal to the longitudinal axis of the rod-shapedarticle 28.

[0061] Without further analysis, the foregoing will so fully reveal thegist of the present invention that others can, by applying currentknowledge, readily adapt it for various applications without omittingfeatures that, from the standpoint of prior art, fairly constituteessential characteristics of the generic and specific aspects of theabove outlined contribution to the art of ascertaining the transversedimensions of rod-shaped articles and, therefore, such adaptationsshould and are intended to be comprehended within the meaning and rangeof equivalence of the appended claims.

What is claimed is:
 1. Apparatus for ascertaining transverse dimensionsof at least one at least substantially rod-shaped article, including anoptical measuring assembly comprising: a radiation source arranged todirect radiation against an article so that the article intercepts aportion of radiation which is indicative of the transverse dimensionthereof, said source comprising at least, one first array of radiationemitting first elements; and an evaluating unit including at least onesecond array of radiation-sensitive second elements located at leastsubstantially opposite said radiation emitting first elements and in thepath of propagation of radiation from said source toward the article togenerate signals denoting the amount of radiation being intercepted bythe article.
 2. The apparatus of claim 1, wherein said first elementsinclude light emitting diodes.
 3. The apparatus of claim 1, wherein saidsecond elements include charge coupled devices.
 4. The apparatus ofclaim 1, wherein the article constitutes at least a portion of arod-shaped smokers' product.
 5. The apparatus of claim 1, wherein saidevaluating unit is arranged to effect a short-lasting determination ofthe transverse dimension of the at least one rod-shaped article in saidpath.
 6. The apparatus of claim 1, wherein the article in said path isstationary.
 7. The apparatus of claim 1, further comprising means foradvancing the at least one article across said path.
 8. The apparatus ofclaim 1, wherein at least one of said first and second arrays at leastpartially surrounds the article in said path.
 9. The apparatus of claim1, wherein at least one of said arrays has an arcuate shape.
 10. Theapparatus of claim 9, wherein said at least one array forms at least aportion of a circle having a center and the article in said path islocated at least close to said center.
 11. The apparatus of claim 10,wherein at least one of said arrays forms a complete circle.
 12. Theapparatus of claim 1, wherein each of said radiation emitting elementshas a first effective width and each of said second elements has asecond effective width less than said first width.
 13. The apparatus ofclaim 1, wherein said optical measuring assembly further comprisescontrol means operatively connected with said source and with said unitand arranged to actuate selected groups of said first elements, toreceive signals from said second elements, and to ascertain thetransverse dimension of the article in said path on the basis of saidsignals.
 14. The apparatus of claim 13 for ascertaining the diameters ofat least substantially rod-shaped articles normally having predetermineddiameters, wherein said control means is arranged to actuate selectedgroups of first elements and each of said groups has a length at leastapproximating one of said predetermined diameters, and to ascertain thediameter of the article in said path on the basis of (a) saidpredetermined diameters and (b) signals from those second elements whichare screened from the groups of neighboring first elements by thearticle in said path.
 15. The apparatus of claim 14, wherein saidcontrol means is arranged to ascertain the diameter of the article insaid path exclusively on the basis of signals transmitted from secondelements which are fully screened from said groups of neighboring firstelements.
 16. The apparatus of claim 13, wherein said first array iselongated and said selected groups of first elements are adjacent eachother, said control means being arranged to actuate successive groups offirst elements and said successive groups forming a row extendinglengthwise of said first array so that the radiation issuing from saidsuccessive groups of first elements impinges at different angles uponthe article in said path.
 17. The apparatus of claim 16, wherein saidfirst array at least partially surrounds the article in said path sothat said successive groups of first elements cause said second elementsto generate signals suitable to be processed by said control unit toascertain the curvature of that portion of the circumference of thearticle in said path which is being exposed to radiation by saidsuccessive groups of first elements.
 18. The apparatus of claim 16,wherein said control means includes means for processing the signalsfrom said second elements into information denoting an averagetransverse dimension of that part of an article which is located in saidpath.
 19. The apparatus of claim 13 for simultaneously ascertainingtransverse dimensions of a plurality of at least substantiallyrod-shaped articles, comprising a discrete optical measuring assemblyfor each of said plurality of articles.
 20. The apparatus of claim 19,wherein the radiation sources and the evaluating units of said discreteassemblies are closely adjacent each other.
 21. The apparatus of claim1, further comprising means for optically separating said first andsecond arrays from each other.
 22. The apparatus of claim 21, whereinsaid separating means comprises at least one diaphragm.
 23. Theapparatus of claim 21, wherein at least one of said arrays forms an atleast substantially complete circle and said separating means comprisesa diaphragm having an opening for the article in said path.
 24. Theapparatus of claim 1, wherein the radiation issuing from said source isat least substantially normal to the longitudinal extension of thearticle in said path.